In the process of analyzing substances and materials in the laboratory, an essential step is the preparation of the sample. This preparatory step is often very time-consuming and expensive, as several samples normally have to be prepared for the analysis of a substance in order to validate the measurement results. In most cases, up to a dozen samples of a given substance have to be weighed into target containers, a solvent has to be added, and the target containers have to be closed up.
To a growing extent, the preparation of samples is being automated in order to shorten the preparation time and to prevent the possibility of errors of the kind that can occur in a manual preparation. Most automated sample preparation systems involve the use of a base platform with individual processing stations and a tri-axial robot system. A multifunctional laboratory instrument of this type is disclosed for example in EP 1 674 393 B1. However, these laboratory instruments have the disadvantage that they require a relatively large work area in comparison to a laboratory balance which is normally used for the manual preparation of samples. If the substances to be processed are toxic, the laboratory balance is set up in a work compartment with an exhaust device and the sample preparation is carried out inside this compartment. However, the aforementioned robot systems are in most cases too big and therefore have their own protective compartment which encloses the entire system. Accordingly, these multifunctional systems cost a multiple of the price of a laboratory balance. Furthermore, due to the size of the working space alone that is enclosed in the protective compartment, the cleaning of these systems involves a significant effort, and if only a small number of samples have to be prepared, the automated sample preparation is therefore still not being used. In contrast, the work compartment of a laboratory balance which is enclosed by the draft shield of the balance can be cleaned quickly and easily.
To alleviate the need for a large amount of working space, the state of the art offers compact laboratory instruments as disclosed for example in EP 1 959 244 A1, FIGS. 7 and 8. A side-by-side arrangement of several dosage-dispensing devices provides a simple way to prepare powder mixtures automatically. Nevertheless, these laboratory instruments, too, require a large working area in comparison to a balance if they are to be enclosed by a work compartment. Furthermore, cleaning of the laboratory instruments arranged in the work compartment is still a big undertaking.